THIS invention relates to a training idler for guiding a travelling conveyor belt as the belt runs along its intended path.
It is well known that conveyor belts tend to drift or creep sideways as they travel along their intended paths. This problem is exacerbated when the belt is particularly long, carries high load, or is a particularly heavy belt. When setting up the belt it is known practice to adjust the alignment of either the drive roller or return roller, or both, to try and achieve central tracking of the belt. However, the belt will often tend to shift laterally at some intermediate point along its length which can cause damage to the edge of the belt or to the support frame.
Also, in use, a belt that has originally been set up to track centrally may, after time, begin to move laterally due to belt stretch, high load situations, or deposits on the rollers. For this reason it is standard practice to have an operator continuously adjusting the angle of the drive or return roller to try and achieve central tracking of the belt. High cost automatic pneumatic or hydraulic adjustors are known, but these are not always appropriate to use, particularly in high load mining operations.
To avoid this continual adjustment it is also known to install tracking rollers, which are also known as training idlers, along the length of the conveyor which will automatically slew about a vertical axis as the belt moves out of alignment to steer the belt back to its central path. US Pat. Nos. 1,510,051, 1,628,614, and 2,725,757 depict examples of known tracking rollers. Each of the tracking rollers depicted in those patents have an upwardly extending guide roller located on opposite edges of the belt. As the belt moves laterally to one or other side the edge of the belt will contact the guide roller on that side which, in turn, will cause pivoting of the training idler to cause the aforementioned pivoting or stewing of the training idler. As the training idler slews out of transverse alignment with the belt it will tend to steer the belt back to its central path whereafter the belt will again run centrally along its intended path.
Various problems are associated with this type of training idler. For example, it is found that the edge of the belt contacting the guide roller tends to place a considerable strain on the guide roller causing damage to the guide roller and the edge of the belt. Also, this type of training idler requires space in which to maneuver so frequently they are inappropriate for installation as a replacement for a standard idler. Thus, if in a particular conveyor it is found that the belt begins to drift at some or other position along the length of the belt it is often necessary to make significant changes to the support frame at the location where it is desired to install a training idler.
It is desirable that where a training idler is to be installed, this can be done with minimum interruption to the operation where the belt is located. It is also desirable that the training idler is relatively inexpensive and uncomplicated so that no special maintenance or skilled operator is required to install and maintain the training idler.